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Published in Zahrah Naankwat Musa, Satellite-Based Mitigation and Adaptation Scenarios for Sea Level Rise in the Lower Niger Delta, 2018
To improve quality of satellite SAR and topographic data, new satellite missions with higher precision instruments are being planned. One of such missions is the Sentinel constellation that will consist of seven satellites; two of which (Sentinel 3 and 6) are especially dedicated to hydrological purposes. Sentinel 1 is already in orbit and undergoing calibration; it has a C-band SAR instrument to continue present C-band data provision. Sentinel 3 is planned to provide fast data for flood emergencies, therefore it has three instruments one of which is a dualfrequency (Ku and C band) advanced Synthetic Aperture Radar Altimeter (SRAL) that will provide accurate topographic data of oceans, ice sheets, sea ice, rivers and lakes (ESA, Sentinel 3, 2015). Sentinel 6, which will complement the Sentinel 3 data, will carry on board a high precision radar altimeter. RADARSAT constellation, a new Low Earth Orbit (LEO) C-band SAR mission is under development by the Canadian space Agency (CSA). The constellation which will have several operating modes will provide interferometric SAR data that can be used for wetlands and coastal change mapping, flood disaster warning and response with resolutions 3, 5, 16, 30, 50 and 100m (Canadian Space Agency (CSA), 2015).
Overview of Hyperspectral Sensors on Orbits
Published in Shen-En Qian, Hyperspectral Satellites and System Design, 2020
The Ocean and Land Color Imager (OLCI) is a VNIR pushbroom imaging spectrometer. It is the successor of MERIS onboard ESA's ENVISAT, which was out of service since Aril 2012. OLCI is one of the seven instruments onboard ESA's Sentinel-3A launched on February 16, 2016. Sentinel-3 is an Earth observation satellite constellation, including two satellites A and B. It is developed by ESA as part of the Copernicus Program of the European Union. The Sentinel-3 mission's main objective is to measure sea-surface topography, sea- and land-surface temperature and color with accuracy in support of ocean forecasting systems, and for environmental and climate monitoring (Donlon et al. 2012).
Planning monitoring programmes for cyanobacteria and cyanotoxins
Published in Ingrid Chorus, Martin Welker, Toxic Cyanobacteria in Water, 2021
Martin Welker, Ingrid Chorus, Blake A. Schaeffer, Erin Urquhart
Current and future operational satellite sensors all have some limited ability to resolve the required geophysical variables but with significant trade-offs among spectral, spatial or temporal resolution (Mouw et al., 2015; Palmer et al., 2015). Here we only mention open-access operational satellites with the highest potential to inform management decisions for inland waters which exist at the time of the publication of this book. These operational satellites generally fall into two categories: (1) medium-resolution ocean colour sensors and (2) higher-resolution land imagers. The medium-resolution ocean colour sensors may include ESA’s Ocean and Land Colour Instrument (OLCI) on the Sentinel-3 (3A launched 2016 and 3B launched in 2018) satellites. Historical data could be retrieved from the MEdium Resolution Imaging Spectrometer (MERIS) on the Envisat satellite from 2002 to 2012. The OLCI and MERIS sensors provide adequate spectral bands for inland water derivation of water quality parameters, with a typical revisit time of 2–3 days, but have spatial resolution (300 m pixel size) limits. Thus, they are useful for providing observations in larger lakes and reservoirs. The higher-resolution land imagers include the Multi-Spectral Instrument (MSI) on the Sentinel-2 (2A launched 2015, 2B launched in 2017) satellites and Landsat series satellites provide the best spatial resolution for inland waters but are at a disadvantage when it comes to spectral resolution, signal-to-noise ratio, and, to some extent, temporal coverage. Only by combining the observations from Landsat missions or Sentinel-2 missions would a temporal revisit of every 8 days and 5 days be possible, respectively. The satellite revisit time is defined as the time between measurements of the same location on the surface of the Earth.
Assessing the impact of SAR altimetry for global ocean analysis and forecasting
Published in Journal of Operational Oceanography, 2018
Simon Verrier, Pierre-Yves Le Traon, Elisabeth Remy, Jean Michel Lellouche
Cryosat-2 launched in 2010 was the first altimeter mission with a SAR mode. Although Cryosat-2 is a mission dedicated to ice studies, its data have been extensively analysed to assess the value of altimeter SAR mode over the ocean (e.g. Boy et al., 2017). Sentinel 3 is a constellation of two ocean missions (S3-A and S3-B) from the European Union Copernicus programme. S3-A was launched in early 2016 and S3-B was launched in spring 2018. They are both equipped with SAR altimetry. By 2020, Sentinel-6 (Jason CS) that will ensure the long-term continuity of the Jason series will also feature a SAR altimetry mode. It is thus expected that in the years to come at least three altimeters with a SAR mode will be flying simultaneously.